present invention relates generally to an improved pneumatic spreader system for distribution of particulate material or granular solids upon the soil, and more particularly to a system for achieving uniform distribution and which is less prone to clogging. This invention is an improvement over that disclosed and claimed in my co-pending application Ser. No. 07/539,866, filed Jun. 18, 1990, entitled "VENTURI SYSTEM FOR AGRICULTURAL SPREADERS OF SOLID PARTICLES", assigned to the same assignee as the present invention.
The arrangement of the present invention achieves a more uniform flow rate of solids at high application rates and through booms of varying lengths within a given distributor. Pressurized pneumatic systems for the distribution of granular or particulate solids are known, and have been used for such purposes in the past, however the systems currently in use at high application rates may deliver or discharge solids through the distributor system at somewhat uneven rates. Particulate solids impregnated with liquid chemical solutions or dispersions have typically been troublesome.
Agricultural techniques require the utilization of soil treating agents to either encourage, discourage, destroy, or inhibit plant growth. Such agents may generally be characterized as crop treating chemicals, and include such materials as nutrients such as fertilizers, and pesticides such as insecticides and pre-emergent or post-emergent plant growth inhibitors. In other words, the term "crop treating chemical" is used in a comprehensive sense to incorporate those various ingredients utilized in agriculture to treat either the soil, plants, or insects. Active materials used for treatment are commonly found in one of three forms, either water soluble, water wettable, or in particulate solid form. In connection with the present invention, particulate solids or granular materials are of interest, with the system of the present invention being adapted for use in connection with the distribution of such materials onto the soil or other surfaces being treated, and further being particularly adapted for use in connection with the distribution of granular materials either at high application rates or when impregnated with liquid mediums, or both.
In the treatment of agricultural fields and crops through spreading of an active treating ingredient, the efficiency of the treatment operation may be enhanced if the load to be carried is reduced. Therefore, the utilization of dry particulate solids will substantially reduce the load requirement, inasmuch as water or other spreading medium or treatment vehicle is not required. The utilization of pressurized pneumatic systems will normally eliminate the need for utilization of water, and with pneumatic systems normally utilizing a compressor in lieu of a liquid pressure source for delivery of the treating ingredient. Additionally, uniform spread rates particularly at high application rates can increase efficiency as well as permitting an increase in the rate at which the treatment vehicle may be driven. Furthermore, when uniform distribution at high application rates can be achieved without necessitating an increase in air velocity, power may be conserved as well.
One common problem encountered with pressurized pneumatic systems for distribution of particulate solids or granular materials is that of uniformity of distribution. This problems becomes aggravated when high application rates are being employed, or when the granular materials are impregnated with other active components in a liquid medium. One factor leading up to lack of uniformity of distribution is a tendency for the granular materials to become lodged in the distribution system, thereby clogging or partially clogging a portion of the system. Such an event will, of course, impede normal air flow through the system. The pressurized pneumatic systems normally employ a plurality of elongated hollow delivery booms, with these booms being of predetermined and differing lengths, and extending laterally outwardly of the supporting vehicle. By extending the length of individual elongated delivery booms on either side of the vehicle, the area of coverage may be correspondingly increased. However, as boom length or application rates increase, problems with clogging, material build-up, and the resulting lack of uniformity of distribution have been found to increase proportionately. The features of the present invention have been found to reduce the tendency to clog even at high application rates, and thus enhance the uniformity of distribution of particulate solids from the system and onto the soil The system further has been found to decrease material build up in certain portions of the system, particularly at the point where particulate solids are being introduced into the delivery booms. Conventional systems have been found to experience pulsating outputs, partial clogging of the boom tubes, and/or material build up, particularly when unusually high application rates are being employed and/or when particulates are of coarse high density materials. The features of the present invention have been found desirable for improving the performance of systems using elongated hollow discharge or delivery booms.
Spreading efficiency and economies of application are improved through use of a system of the present invention. Vehicles may be driven at significantly higher rates of speed, inasmuch as uniformity of spreading rates are preserved. Spreading rates are, of course, inversely proportional to vehicle speed, and application accuracy is preserved whenever uniform discharges are achieved.